Electric lighting



(No Model.)

R. M. HUNTER. ELECTRIC LIGHTING Patented Mar. 24, 1891.

Unirno STATES PATENT OFFICE.

RUDOLPH M. HUNTER, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO THETHOMSON-HOUSTON ELECTRIC COMPANY, OF CONNECTICUT.

'ELECT'REC LiGHTlNG.

SPEGEFICATION forming part of Letters Patent No. 448,782, dated March24, 1891.

Application filed December 30, 1890. Serial No. 376,201. (No model.)

To (aZZ 1071mm it 17mg concern:

Be it known that I, RUDOLPH M. HUNTER, of the city and county ofPhiladelphia, and State of Pennsylvania, have invented an Improvement:in Electric Lighting, of which the following is a specification.

My invention has reference to electric lighting; and it consists ofcertain improvements which are fully set forth in the followingspecification and shown in the accompanying d rawings, which form a partthereof.

This application (Case 186) comprehends an improved system of serieslighting with the employment of continuous or alternating currents, andespecially adapted to incandescent lamps.

In carrying out my invention I arrange the lamps in series or in seriesmultiple, so that the current passing through one lamp traverses thenext. Around each lamp 1 place a shunt containing an automaticresistancechanger which shall reduce the resistance in the shuntwhenever the corresponding lamp shall be cut out of circuit by breakageof the lamp or otherwise.

In the employment of incandescent lamps in series lighting considerablediiliculty has been experienced in insuring the proper sup ply ofcurrent to the line containing the other lamps upon any lamp giving out.

The object of my invention is to provide a method and means formaintaining the circuit in proper condition for the continued operationof the remaining lamps after the destruction of one or more lamps of theseries. The current in the line is greater than that required in any onelamp in the series, and part of this current I shunt about each lamp,the resistance of the shunt being so proportioned that allot the currentnecessary for the lamp will pass through it. In addition to thislast-mentioned resistance 1 provide an auxiliary resistance-reducerwhich shall still further reduce the resistance to the line-current uponthe rupture of the lamp filament or other cutting of the lamp outofcircuit. This auxiliary resistance is cut out or reduced by the actionof the heat produced by the heavy duty upon the shunt when the lamp iscut out. When the shunt is unduly heated by too great a flow of current,an expansible or 'aporizable conducting substance like mercury is causedto either expand or vaporize, and thus reduce the resistance in theshunt about the lamps.

Several ways of accomplishing the reduction of the shunt-resistanceembodying my invention are fully set out hereinafter.

Referring to the drawings, Figure 1 is a diagram showing acontinuous-current dynamo and line-circuit with lamps in series. Fig. 2is a similar view showing an alternating-current generator and the lampsin series multiple. Fig. 3 is a side elevation, with part in section, ofthe circuits and shunting devices for each lamp. Fig. a is across-section of a modified form of resistance-reducer for theshunt-circuit, and Fig. 5 is an elevation of still another modificationof. the resistancereducer.

A is the electric generator, which may be a continuous-currcnt machine,as shown in Fig. 1, or an alternate-currcut machine. as shown in Fig. 2.

B is the linecircuit and contains the lamps D in series. This circuit isalso provided, it desired, with a regulator (l. The lamps may be insimple series, as shown in Fig. 1, or in series multiple, as shown inFig. 2. The lampcircuit B in Fig. l and Bin Fig. 2 is provided with ashunt-circuit F to each lamp, so that part of the current passes throughthe lamp and part through the shunt-circuit, which acts as a by-pass tothe current in the line-circuit. The shunt-circuit is provided with anautomatic resistance-reducer device E for reducing the resistance toflow of current about the lamp in case the lamp is outof order, brokenor cut outby a switch 0. The resistance-reduccr may be made in a varietyof ways, but in all cases depends upon the expansion of a conductingmedium, be that expansion manifested in only a change of volume of thesubstance or a change in form by vaporization.

Referring to Fig. 3, G is a vessel of iron or glass and contains mercuryor other conducting substance S capable of expansion by application ofheat. Surrounding this vessel is a coil H in the shunt F. The shuntconnects with the mercury S by a conductor I or in any other suitableway. A conductor .l,-in-

sulated from vessel G, extends down from the top close to the normallevel of the mercury and connects by a conductor K directly or through aresistance 7t wit-h the shunt F, as shown.

When the lamp E is burning, the current divides, part passing throughthe lamp and part through the shunt F. If the lamp is broken or cutout,the whole current passes over the shunt F and heats the mercury S,causing itto rise in the vessel and make a contact with the conductor J,reducing the resistance to the line-current. The enlarged top 9 of thevessel G is to allow the mercury to expand without abnormally risingwhen expanding. If the vessel G is of glass, the

- wire coil H need not be insulated; but if of iron then there should bean insulation either of the vessel or of the coil.

In the" construction shown in Fig. 4 the shunt F is provided with a coilH, which is inclosed and insulated from a glass or iron cylinder G. Thevessel is horizontal and contains mercury or other conducting substancecapable of conducting electricity. If an abnormal current passes overthe coil H it heats it, and this vaporizes the mercury and instantlyreduces the resistance produced by the coil. If iron is employed in thevessel G, then the vessel itself will be heated and vaporize themercury, the vapors thereof surrounding the coils H and offering a pathof less resistance. porizable substance S does not touch the coil.

In place of the devices shown in the above figures that shown in Fig. 5might be used. In this case a tube or vesselG of iron incloses aconductor J, which is bare, but insulated from the tube G. The shunt Fencircles the tube, as in the case of Fig. 3, and heats it. Theconductor J is connected with the distant end of the shunt, and theother end of the shunt is electrically connected with the iron tube G.When the tube is heated by the excess of current flowing through thecoil H, the mercury or other conducting substance is vaporized withinthe tube and forms a conducting-path from the tube to the conductor J,reducing the normal resistance of the shuntcircuit to compensate forthe'increase of the resistance put on the line by the destruction of thelamp. The mercury-level under nor Normally the mercury or va-.

mal conditions is indicated by the dotted line S. Fig. 5 is practicallythe device E shown in Fig. 3 turned on its side.

Ido not limit myself to the minor details of construction, as they maybe modified in various ways without departing from the principles of myinvention.

Having now described my invention, what I claim as new, and desire tosecure by Letters Patent,- is- 1. The combination of a linecircuit, anelectric lamp connected therein in series, a shunt-circuit in theline-circuit about said electric lamp, a heating-coil arranged in saidshunt-circuit, a receptacle having fixed terminals connecting with theline-circuit, and an expansible fluid-conducting substance'in saidreceptacle adapted to be expanded upon an excessive current passingthrough the heating-coil for the purpose of reducing the resistance tothe passage of current in the line in case the lamp should burn out.

2. The combination of a line-circuit, an

electric lamp arranged in series connection therewith, a shunt-circuitaround the lamp and connecting with the line-circuit and including aheating-resistance, a receptacle inclosing said resistance, and anexpansible substance within the receptacle adapted to be heatedupon anexcessive current being passed through the resistance by breakage of thelamp.

3. The combination of a'line-circuit, an electric lamp in seriestherein, a shunt-circuit around the lamp, whereby the line-current isdivided and part passed through the lamp and part through theshunt-circuit, a resistance in the shunt-circuit, a closed vessel having two fixed terminals connecting with the line on opposite sides ofthe resistance, and an expansible fluid-conducting substance in thereceptacle adapted to reduce the resistance between the two terminalsupon the resistance in the shunt-circuit upon becoming abnormally heatedupon breakage of the lamp.

In testimony of which invention I have hereunto set my hand.

' R. M. HUNTER. Witnesses:

ERNEST HOWARD HUNTER, S. '1. YERKES.

